GIS-based decision support system for real time water demand estimation in canal irrigation systems

Abstract

In canal irrigation systems in India, water supplies reach the fields through a network of main canals, branch canals (secondary canals) and distributaries (tertiary canals). The distributary is the basic unit of irrigation management in large canal systems, as it is the last point of control in main irrigation systems operation. This study presents a scheme for the development of a Geographic Information Systems (GIS)based decision support system (DSS) for real time water demand estimation in distributaries. The DSS dynamically links a field irrigation demand prediction model for the area irrigated by a distributary with a GIS of the canal network. The system allows interactive selection of distributaries and on-line real time estimation of water demands in each distributary over the entire network. For real time estimates, the model is used with current season information on weather, weather forecasts and distributary level information on crops and soils. Since the distributary is the unit of operation, the DSS integrates well with the actual process of decision-making by the operators of canal irrigation systems in India. The availability of such a quantitative decision-support tool for irrigation systems operation can have a powerful impact on the overall water management strategy to be adopted in an irrigation project area, particularly in the event of a shortfall in water supplies. The development of the overall scheme and procedures is illustrated with data from a case study area in India.